This invention relates to apparatus and method for recognizing an individual and/or for verifying an individual's identity. It pertains particularly to an apparatus for obtaining an identification pattern from the ocular reflection from the fundus of the eye of an individual, irrespective of head-tilt.
My previous patent, U.S. Pat. No. 4,109,237 discloses a basic method and apparatus for identifying individuals through their retinal vasculature patterns. My subsequent patent, U.S. Pat. No. 4,393,366, discloses using a rotating beam scanner for obtaining the identification pattern from the fundus of an eye.
Previously, it was believed that the identification pattern, carrying sufficient information, could be obtained best by centering on the optic nerve. In that way the blood vessels emerging from the optic nerve and forming the retinal vasculature could be used for obtaining the individual identification pattern. However, it has been found that by the use of infrared radiation the vasculature of the choroid becomes readily and accurately detectable. The choroidal vasculature forms a matting behind the retina even in the area of the macula and fovea, where retinal blood vessels are very small or non-existent. The blood vessels of the choroid are stable, as are those of the retina, and thus may be used for obtaining information as to an individual's identity.
The eye naturally fixates and centers images on the fovea. When fixating on any target the eye comes to a position with its visual line passing through the center of the eye and intersecting the fovea. However, the optic nerve enters the eye off axis, approximately 15.5 degrees toward the nasal side of the eye. In my previous patents an off-axis scanner was disclosed which caused a scan to be taken around the optic nerve while the eye was fixated on the fovea.
However, it has been found that a problem at times is encountered in obtaining consistent identification patterns with a given subject. The problem is caused by rotation of the eye about its visual line when the subject tilts his head. In the off-axis scanner a different part of the eye will be scanned if the head is tilted. It is true that as the head tilts the eye has a tendency to right itself to a level position. However, this tendency is not sufficiently accurate to compensate entirely for head tilt. Accordingly, it is necessary for the subject to locate his head in almost exactly the same rotational position each time a scan is made.
The present invention overcomes this difficulty.
It is the general object of this invention to provide an improved apparatus and method for obtaining and recording an identification pattern from the reflection of light from the fundus of an eye.
It is another object to provide such an apparatus which takes a circular scan centered on the eye fovea.
It is another object to provide an infrared light source which will detect the vasculature of the choroid and which will not affect pupil dilation during the pattern-recording scan.
It is yet another object to provide a fixation apparatus which will repeatably position the eye and orient it along its visual line.
It is a further object to provide a fixation means which is operable to cause the pupil to dilate or constrict.
It is another object to provide correct optical refraction or focus for each user.
It is a still further object to pass the fixation, source and reflected beams through common optical elements on a common visual axis, thereby reducing the complexity and cost of the apparatus.
These and other objects and advantages of the present invention and the manner in which they are achieved will be made apparent in the following specification and claims.